Both Payne and Hardies say that they don't measure progress by just the minds they might change, but by how successful they are in changing the tenor of the dialogue.

"We're trying to get the message across about gay marriage being about love, and the benefits that come from that," she says.

Assuring ministers that supporting or being agnostic on the issue of same-sex marriage doesn't mean they have to perform such ceremonies in their churches has also helped, they say.

"One thing that really troubles us is that Marion Barry said this would be a civil war," Hardies said. "War is not the right way to talk about an issue that involves love."